The present invention relates to wheelchairs and, in particular, to a wheelchair having a drive and steering linkage whereby a wheelchair bound user with a single hand and small hand movement can drive a small diameter idler wheel, independent of large diameter hand drive wheels, to rotate the idler wheel and steer the chair.
A wide variety of wheelchairs exist for conveying geriatric and non-ambulatory individuals. Most chairs provide for a pair of relatively large diameter wheels that contain concentric hand rails. The rails can be grasped, rotated and/or manipulated by the user to drive and direct the chair. Most chairs also provide a pair of smaller diameter idler or non-driven wheels that typically support the front end of the chair. The idler wheels stabilize the chair and distribute the weight of the user. The idler wheels are mounted to rotate in associated support columns and follow motions directed by the larger diameter drive wheels
A variety of after-market and integrated assemblies have also been developed to provide drive power to the drive wheels of a wheel chair. Many assemblies actively drive the chair with the aid of a battery power source and associated drive linkage.
Many ratchet and lever arm accessories also exist in the art that apply drive power to the large diameter drive wheels without having to grip the hand rings. For example, U.S. Pat. No. 5,232,236 and published applications 2002/0043781; 2005/0269797; 2005/0275190; and 2006/0261571 disclose some of these assemblies. Some assemblies provide for foot and hand crank operation. U.S. Pat. Nos. 5,297,810; 5,873,589; 6,196,565;
A variety of hand manipulated lever arm assemblies have also been developed for wheel chairs that include drive linkages that cooperate with the large diameter wheel drive axles. To and fro movement of one or more included lever arms mounted to pivot at the chair direct associated linkages (e.g. chain, belt and rod) coupled to supporting axles to drive the large diameter wheels. Some of these assemblies can be found at U.S. Pat. Nos. 4,641,847; 4,762,332; 5,007,655; 5,020,815; 5,236,398; 5,322,312; 5,499,833; 6,325,398; 6,715,7890; 6,746,034; and 6,820,885. An arm rest that pivots side to side and cooperates with an eccentric coupled link rod is disclosed at U.S. Pat. No. 5,509,673.
A hand crank assembly that rotates about one axis to supply drive power to a depending chain and independently rotates about a second axis to provide steering to a large diameter drive wheel is shown at US published application 2006/0131832. A pivoting lever arm assembly and chain linkage that cooperates with a large diameter drive wheel and separately provides a rotating steering hand hold that cooperates with a small diameter idler wheel is shown at U.S. Pat. No. 6,916,032.
In contrast to the foregoing, the present invention provides a multi-axial hand-operated lever arm that pivots with limited hand movement in one axis (i.e. Y axis) to couple drive power via a rigid drive arm to a one-way clutch and small diameter drive wheel. Reciprocating vertical movement of the hand arm particularly supplies drive power to an eccentric arm fitted to the one-way clutch and a drive axle of a small diameter, secondary drive wheel. The hand arm independently rotates 360° about a horizontal or Z axis within a support column to steer the associated secondary drive wheel. Large diameter, primary drive wheels with hand rings are separately available to the user for normal conveyance.